For example all windows don’t open (all windows have new blinds) , wiring exposed under the sink, rotten wood , damaged shingles , unlevel sidewalk, exposed romex wiring in laundry rm, damaged siding , & no drain pan for water heater .

The work would require tearing off the old layers of shingles, putting down new plywood, new shingles and new metal flashing.

Needs to be gutted, needs new roof, new hvac, new windows, new drywall, fix water damage throughout, rebuild an addition, add a garage, add a 2nd bathroom, new flooring, new kitchen, new appliances, paint, landscaping, redo driveway, redo layout (used to be a triplex but is now sfh), remediate sinkhole, replace asbestos shingles with siding, upgrade electric from fuse box, replace cast iron pipes throughout, put in a pool. 

Don't quote me, but I think appliances are depreciated over 5 years and roofs maybe 25 years (may depend on the type of shingle).Oh, I agree about the tax implications of depreciation recapture. 

I asked my insurance agent how filing a claim would affect my rate and she was completely useless, basically saying that nobody knows how my rate would be affected because it is determined by a computerized algorithm.

Leaking valleys, dormers, lack of maintenance on flat roof surfaces, missing shingles/shakes all can create leaks that will run all the way down through the house, rotting framing, flooring, damaging ceilings and anything else the water comes in contact with from the very top to the very bottom of your structure.

Missing shingles in the roof- Is this something a handy man can fix?

Let's say you have a 5 building complex and each building needs a new shingle roof at a cost of $20,000 per building ($100k project). 

The useful life of an asphalt shingle roof is 20 years, so assuming a new roof may cost $4000 in 20 years, save up $16-20/month and then you'll have enough to replace it in 20 years.

Installing multiple layers of shingles reduces the life of the shingles.